KR20060102360A - Optical sheet and back light unit including the same - Google Patents

Abstract

The present invention relates to an optical sheet and a backlight unit having the same.

An optical sheet according to an embodiment of the present invention is characterized in that it comprises a support layer for transmitting light incident from the outside, and a reflective layer formed on the support layer, partially exposing the support layer and having an inclined surface.

Description

Optical Sheet And Back Light Unit Including The Same

1 is a view showing a conventional liquid crystal display device.

FIG. 2 is a cross-sectional view illustrating a cross section taken along the line II-II ′ of FIG. 1.

3 is a view showing a conventional optical member.

4A and 4B are diagrams showing a light distribution diagram by a conventional optical member.

5 is a view showing an optical member according to a first embodiment of the present invention.

6 is a view showing an optical member according to a second embodiment of the present invention.

7A and 7B illustrate an optical member according to a third exemplary embodiment of the present invention.

8 is a view schematically showing a path of light irradiated from an external light source.

9 is a view showing an optical member according to a fourth embodiment of the present invention.

10 is a cross-sectional view taken along the line VII-VII ′ of FIG. 9.

11 is a view illustrating a backlight unit having an optical member and a liquid crystal display including the optical member according to an exemplary embodiment of the present invention.

FIG. 12 is a cross-sectional view taken along the line II-XII 'of FIG. 11. FIG.

<Description of Symbols for Main Parts of Drawings>

2, 102: liquid crystal display panels 8, 18, 108, 118: polarizing sheet

10 optical sheet 12 diffuser plate

14, 114: reflector 34, 134: case

36, 136: lamp 110, 210, 310, 410, 510: optical member

120, 220, 320, 420: support layer 140, 240, 340, 440: reflective layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical sheet and a backlight unit, and more particularly, to an optical sheet and a backlight unit capable of improving contrast by improving light collection efficiency.

In general, liquid crystal displays (hereinafter referred to as "LCDs") have tended to be increasingly wider in application due to features such as light weight, thinness, and low power consumption. According to this trend, LCDs are used for office automation equipment, audio / video equipment, and the like. On the other hand, the LCD is controlled to display the desired image on the screen by adjusting the transmission amount of the light beam according to the image signal applied to the plurality of control switches arranged in a matrix form.

Since the LCD is not a self-luminous display device, a light source such as a back light is required. Such LCD backlight has a direct type and an edge type. In the edge type system, a lamp is installed outside the flat plate, and light is incident from the lamp onto the entire surface of the liquid crystal display panel using a transparent light guide plate. The direct type places several lamps in the plane. A diffusion plate is provided between the lamp and the liquid crystal display panel to maintain a constant space between the liquid crystal display panel and the lamp. On the other hand, according to the type of lamp, the cold cathode tube ("CCFL") method of supplying power by inserting electrodes at both ends of the glass tube of the lamp, and the metal tube of both ends of the glass tube of the lamp There is an external electrode fluorescent lamp ("EEFL") that supplies power to the surrounding electrode.

1 and 2 show a conventional LCD.

1 and 2, a conventional LCD includes a liquid crystal display panel 2 for displaying an image and a backlight unit for irradiating uniform light onto the liquid crystal display panel 2.

In the liquid crystal display panel 2, liquid crystal cells are arranged in an active matrix between upper and lower substrates, and pixel electrodes and a common electrode for applying an electric field to each of the liquid crystal cells are provided. Each of these pixel electrodes is connected to a thin film transistor used as a switch element. The pixel electrode drives the liquid crystal cell along with the common electrode according to the data signal supplied through the thin film transistor to display an image corresponding to the video signal.

The backlight unit includes a case 34, a reflecting plate 14 stacked on the front of the case 34, a plurality of lamps 36 positioned on the reflecting plate 14, and a plurality of lamps 36. The diffuser plate 12 and the optical sheet 10 which are arrange | positioned are provided.

The case 34 converts a path of light generated from the lamps 36 by reflecting visible light traveling toward the side and the back of the plurality of lamps 36 toward the front side, that is, the diffuser plate 12.

The reflective plate 14 is disposed between the upper surface of the case 34 and the plurality of lamps 36 to reflect the light generated from the lamps 36 and to be irradiated toward the liquid crystal display panel 2 to improve the light efficiency. .

Each of the plurality of lamps 36 includes a glass tube, inert gases inside the glass tube, and a cathode and an anode portion made of metal covering both ends of the glass tube. These multiple lamps 36 are arranged side by side on the case 34.

The diffusion plate 12 allows the light emitted from the plurality of lamps 36 to propagate to the liquid crystal display panel and to be incident at a wide range of angles.

The optical sheets 10 may improve the front brightness of the liquid crystal display and reduce power consumption by narrowing the viewing angle of the light emitted from the diffuser plate 12.

Conventional liquid crystal display devices having such a structure have a lot of problems in achieving high luminance due to poor light transmittance of the polarizing plates 8 and 18 and the liquid crystal. Accordingly, although the optical sheet 10 for achieving high brightness as shown in FIG. 3 has been proposed, the optical sheet 10 shown in FIG. 3 has a side lobe as shown in FIGS. 4A and 4B. It has the same problem of light loss as Lobe). Accordingly, there is an urgent need for an optical member capable of reducing light loss due to side lobes and improving contrast by improving light condensing efficiency of light generated from the lamps 36.

Accordingly, it is an object of the present invention to provide an optical sheet and a backlight unit having the same that can improve contrast by achieving efficiency of condensing.

In order to achieve the above object, an optical sheet according to an embodiment of the present invention is provided with a support layer for transmitting light incident from the outside, and a reflective layer formed on the support layer and partially exposing the support layer and having an inclined surface. Characterized in that.

The reflective layer has a first cross-section triangular pillar extending in the longitudinal direction is arranged at a predetermined interval, the second cross-section triangular pillar extending in the longitudinal direction is arranged in the form of a lattice, and a triangular pyramid shape It is characterized in that at least one of the third form in which the elongated pyramid prism is arranged in a predetermined direction, each array is spaced apart, and the fourth form in which the pyramidal prism extending in a triangular pyramid form arranged in a lattice form.

The reflective layer is arranged at regular intervals, characterized in that formed in at least one of the trapezoidal shape and the rounded rounded shape of the corner of the triangular prism and triangular pyramid shape.

The region in which the reflective layer is in contact with the support layer may transmit light incident from the outside.

The reflective layer may be formed of a metallic material such as nickel (Ni), chromium (Cr), aluminum (AL), or aluminum oxide (Al ₂ O ₃ ), a nonmetallic material such as reinforced plastic, glass, or acryl, and the diffusion layer. Characterized in that formed at least one of the materials to be formed.

The support layer is characterized in that the diffusion layer for diffusing light incident from the outside.

An optical sheet according to an embodiment of the present invention includes a support layer through which light is transmitted, and a protrusion integrated with the support layer and protruding with an inclination from the surface of the support layer and arranged such that the support layer is partially exposed. It is characterized in that the reflective surface treatment.

In the backlight unit according to an embodiment of the present invention, a backlight unit in which a plurality of light sources are installed in a liquid crystal display device is formed on a support layer and a support layer for transmitting light incident from the outside and partially exposes the support layer. In addition, an optical sheet having a reflective layer having an inclined surface is provided.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

5 is a view showing an optical member 110 according to a first embodiment of the present invention.

Referring to FIG. 5, the optical member 110 according to the first exemplary embodiment includes a support layer 120 through which light is transmitted and a reflective layer 140 formed in a predetermined pattern on the support layer 120.

The support layer 120 may be formed of a transparent sheet that transmits light input from the outside, and also allows the light emitted from an external light source to propagate to the liquid crystal display panel 102 and is incident at a wide range of angles. It can be formed into a diffusion layer that allows. The support layer 120 has a plurality of beads (beads) formed therein to diffuse the light generated from the external light source, thereby extending the emission range of the light emitted from the surface of the support layer 120. The material of the support layer 120 may include at least one of a transparent sheet such as a transparent acrylic resin and tempered glass, or an optical resin such as polymethylmethacrylate (PMMA), polycarbonate (polycarbonate), and methyl methacrylate-styrene copolymer (MS resin). It is formed as one.

Reflective layer 140 is arranged to partially expose support layer 420. The reflective layer 140 has a triangular cross section and is elongated in the longitudinal direction in order to improve the light condensing efficiency of light irradiated from the rear surface of the support layer 120 to have a prism shape of a triangular prism as a whole. A plurality of such reflective layers 140 are arranged at predetermined intervals on the support layer 120. The angle and length of the triangle in the cross section of the reflective layer 140 may be set in various ways according to the conditions of the display device including the optical member 110. Specifically, the size of the optical member 110 is set differently according to the size and shape of the display device, and at the same time, the distance between the optical member 110 and the light source is set differently. As a result, the area to be collected through the optical member 110 is not determined at a predetermined distance from the light source, and may be set differently according to the external condition and optical characteristics of each display device. Accordingly, the angles of the three vertices of the triangle and the length of the three sides of the triangle in the cross section of the triangular prism according to the first exemplary embodiment of the present invention may be set differently according to external conditions of each display device. As the material of the reflective layer 140, various materials capable of converting the inclination angle of light radiated from the outside may be used. For example, at least one of metallic reflective materials such as nickel (Ni), chromium (Cr), aluminum (AL), and aluminum oxide (Al ₂ O ₃ ), or may form the reinforced plastic, glass, acrylic, and support layer 120. It may be formed of at least one of the materials.

In the optical member 110 according to the first embodiment of the present invention having the structure as described above, the reflective layer 150 is formed on the support layer 120 to reflect the light, and the reflective layer is not formed so that the optical member 110 This has a transmission area 160 that is directly transmitted.

By reflecting the light irradiated from the light source to the reflective region 150 is recycled (Recycling) to a reflector, etc. that can be formed on the back and side of the light source to be re-condensed.

Two light beams irradiated from the light source, that is, straight light beams 160a passing straight through the support layer 120, and oblique light beams irradiated toward the side surfaces of the support layer 120 when viewed from the transmissive area 160, 160b) is transmitted. Here, the straight light 160a is transmitted through the support layer 120 to be directly irradiated directly to a specific target on the top. In addition, the inclined light 160b is irradiated from the side of the straight light 160a to pass through the support layer 120, and then irradiated to the side of the reflective layer 140 so that the emission angle is changed on the surface of the reflective layer 140. The inclined light 160b whose emission angle is converted on the surface of the reflective layer 140 is irradiated to a specific target on the top, almost similar to the straight light 160a.

6 is a view showing an optical member 210 according to a second embodiment of the present invention.

Referring to FIG. 6, the optical member 210 according to the second exemplary embodiment includes a support layer 220 and a reflective layer 240 formed in a predetermined pattern on the support layer 220.

The support layer 220 allows the light irradiated from the external light source to propagate to the liquid crystal display panel 202 and can be incident at a wide range of angles. The support layer 220 has a plurality of beads (beads) formed therein to diffuse the light generated from the external light source, thereby extending the emission range of the light emitted from the surface of the support layer 220. The support layer 220 may be made of at least one of a transparent sheet such as a transparent acrylic resin and tempered glass, or an optical resin such as polymethylmethacrylate (PMMA), polycarbonate, and methyl methacrylate-styrene copolymer (MS resin). Is formed.

The reflective layer 240 has a triangular cross section and extends in the longitudinal direction in order to improve the light condensing efficiency of light irradiated from the rear surface of the support layer 220 so that the prism shape of the triangular prism is arranged in a lattice form as a whole. The angle and length of the prism triangle in the cross section of the reflective layer 240 may be set in various ways according to the conditions of the display device including the optical member 210. Since the conditions for forming the reflective layer 240 are the same as the conditions according to the first embodiment of the present invention, description thereof will be omitted. As a material of the reflective layer 240, various materials capable of converting the inclination angle of light emitted from the outside may be used. For example, at least one of metallic reflective materials such as nickel (Ni), chromium (Cr), aluminum (AL), and aluminum oxide (Al ₂ O ₃ ), or may form the reinforced plastic, glass, acrylic, and support layer 220. It may be formed of at least one of the materials.

Here, the optical member 210 according to the second embodiment of the present invention is a reflection layer 240 is not formed in the center of the prism of the triangular prism arranged in the form of a lattice, the transmission region 260 is directly transmitted through the light, and the support layer The reflective layer 240 is formed on the 220 to have a reflective area 250 that reflects light.

By reflecting the light irradiated from the light source on the back of the reflective area 250 is recycled (Recycling) to a reflector, etc. that can be formed on the back and the side of the light source (recycling).

Two light beams irradiated from the light source are transmitted to the light transmission area 260, that is, straight light 260a for passing straight through the support layer 220, and inclined light emitted to the side of the support layer 220 when viewed from the transmission area 260. 260b) is transmitted. Here, the straight light 260a is transmitted through the support layer 220 to be directly irradiated directly to a specific target on the top. In addition, the inclined light 260b is irradiated from the side of the straight light 260a to pass through the support layer 220, and then irradiated to the side of the reflective layer 240 so that the emission angle is changed on the surface of the reflective layer 240. The inclined light 260b whose emission angle is converted on the surface of the reflective layer 240 is irradiated to a specific target on the top, almost similar to the straight light 260a.

In the optical member 220 according to the second embodiment of the present invention having the structure as described above, since the reflective region 250 surrounding the transmission region 260 is formed in a quadrangular shape, the light condensing property of the light emitted from the light source is further increased. It can be improved.

7 is a view showing an optical member 310 according to a third embodiment of the present invention.

Referring to FIG. 7, the optical member 310 according to the third exemplary embodiment includes a support layer 320 and a reflective layer 340 formed in a predetermined pattern on the support layer 320.

The support layer 320 allows the light irradiated from the external light source to travel to the liquid crystal display panel 302 and to be incident at a wide range of angles. The support layer 320 has a plurality of beads formed therein to support the light generated from an external light source, thereby extending the emission range of the light emitted from the surface of the support layer 320. The material of the support layer 320 according to the third embodiment of the present invention may be formed of the same material as the material of the support layer described in the first and second embodiments of the present invention.

The reflective layer 340 has a triangular pyramid-shaped prism arranged in one direction or a lattice in order to improve the light condensing efficiency of light irradiated from the rear surface of the support layer 320. The angle and length of the prism triangle in the cross section of the reflective layer 340 may be variously set according to the conditions of the display device including the optical member 310. Since the forming conditions of the reflective layer 340 are the same as the conditions according to the first embodiment of the present invention, description thereof will be omitted. As the material of the reflective layer 340, various materials capable of converting the inclination angle of light emitted from the outside may be used. For example, at least one of metallic reflective materials such as nickel (Ni), chromium (Cr), aluminum (AL), and aluminum oxide (Al ₂ O ₃ ), or reinforced plastic, glass, acrylic, and support layer 320 may be used. It may be formed of at least one of the materials to be formed.

Herein, the optical member 310 according to the third embodiment of the present invention replaces the shape of the reflective layer 340 from a triangular prism to a triangular pyramid shape as compared with the first and second exemplary embodiments of the present invention. Except for arranging in one direction and lattice form, the same configuration will be omitted.

The optical member 310 according to the third embodiment of the present invention having the structure as described above may further improve the light condensing property of the light emitted from the light source by providing the reflective area 350 to surround the transmission area 360. Will be.

8 is a view illustrating a light path through which light travels through the optical members 110, 210, and 310 according to the first to third embodiments of the present disclosure.

Referring to FIG. 8, light moving through the optical members 110, 210, and 310 according to the first to third embodiments of the present invention may be moved straight through the support layers 120, 220, and 320. 360a, and the inclined light (160b, 260b, 360b,) moving after the path of the light is changed by the reflective layers (120, 220, 320) and the recycling reflected by the back of the reflective layers (120, 220, 320) Light 360c. As a result, the light is condensed through the optical members 110, 210, and 310 according to the first to third embodiments of the present invention and then irradiated to a specific target on the upper side, thereby exhibiting excellent light condensing efficiency.

9 and 10 illustrate an optical member 410 according to a fourth embodiment of the present invention.

9 and 10, the optical member 410 according to the third exemplary embodiment includes a support layer 420 and a reflective layer 440 formed in a predetermined pattern on the support layer 420.

Since the support layer 420 according to the fourth embodiment of the present invention has the same structure as the support layer 320 described in the optical member 310 according to the first to third embodiments of the present invention, description thereof will be omitted.

Reflective layer 440 is arranged to partially expose support layer 420. Accordingly, the support layer 420 is divided into a reflection area 450 in which the reflection layer 440 is arranged and a transmission area 460 in which the reflection layer 440 is not arranged, and the light incident on the rear surface of the reflection layer 440 is reflected by the reflection layer ( The light is reflected from the inside of the 440 and is not transmitted to the outside, and the angle of the incident light is changed with an angle from the transmission area 460. That is, the light incident from the outside is transmitted through the reflective layer 440 without being reflected by the contact portion that contacts the support layer 420, and then is reflected by the inner surface of the reflective layer 440 other than the contact portion. The reflective layer 440 may be similarly applied to the triangular pyramid-shaped arrangement described in the second and third embodiments of the present invention. That is, in the optical member 410 according to the fourth embodiment of the present invention, the back surface of the triangular pyramid contacting the support layer 420 is not subjected to the reflection surface treatment, and the reflection surface treatment is performed only in the region not in contact with the support layer 420. .

In addition, the optical member 410 according to the fourth embodiment of the present invention may be integrated with the support layer 420 and the reflective layer 440 through which light passes. Specifically, the triangular prism and the triangular pyramid-shaped protrusions described in the first to third embodiments of the present invention are integrated with the support layer 420 and protrude with an inclination from the surface of the support layer 420. The protrusion may be arranged to partially expose the support layer 420, and the reflective layer 440 may be formed by reflecting the surface of the protrusion. That is, the optical member 410 according to the fourth embodiment of the present invention may form the optical member 410 by reflecting the support layer 420 and the surface of the protrusion partially protruding from the surface of the support layer 420. Can be. Accordingly, the flat surface of the support layer 420 has a straight light 460a and an inclination and becomes a transmission region 460 through which the inclined light 460b is transmitted, and the protruding region of the support layer 420 reflects light. It becomes the reflection area 450.

In the optical member 410 according to the fourth embodiment of the present invention having the structure as described above, the area in contact with the support layer 420 does not have a reflective surface treatment, and reflects light incident at an angle from the transmission area 460. As a result, the optical member 410 is easy to manufacture, and the same effects as those described in the first to third embodiments of the present invention can be achieved.

In addition, the reflective layers 140, 240, 340, and 440 of the optical members 110, 210, 310, and 410 described in the first to fourth embodiments of the present invention may pass through the transmission regions 160, 260, 360, and 460. The purpose of the present invention is to change the angle of incident light with an angle, so that the edges of the reflective layers 140, 240, 340, and 440 are not sharply formed but are rounded, rounded, or have a trapezoidal structure as a whole. You can achieve your purpose. Herein, the optical members 110, 210, 310, and 410 according to the first to fourth embodiments of the present invention may measure the size of the transmission region 460, that is, the aperture ratio and the inclination of the reflective layers 140, 240, 340, and 440. By adjusting, desired luminance distribution can be obtained, respectively.

11 and 12 are views illustrating a liquid crystal display device including the optical members 110, 210, 310, and 410 according to the first to fourth embodiments of the present invention.

11 and 12, the liquid crystal display according to the embodiment of the present invention includes an optical member according to each embodiment of the present invention to irradiate light to the liquid crystal display panel 102 and the liquid crystal display panel 102. And a backlight unit including 510.

In the liquid crystal display panel 102, liquid crystal cells are arranged in an active matrix form between upper and lower glass substrates, and thin film transistors for switching video signals are provided in each of the liquid crystal cells. It is. The liquid crystal display panel 102 may display an image corresponding to the video signal by changing the refractive index of each of the liquid crystal cells according to the video signal. A tape carrier package (not shown) in which a driver integrated circuit for applying a driving signal to a thin film transistor is mounted on the lower substrate of the liquid crystal display panel 102 is attached. In addition, polarizing sheets 108 and 118 are provided on the front and rear surfaces of the liquid crystal display panel 102, respectively. Here, the polarizing sheets 108 and 118 function to improve the viewing angle of the image displayed by the liquid crystal cells.

The backlight unit receives power from an external power source and includes a plurality of lamps 136 for irradiating light to the liquid crystal display panel 102, a case 134 for storing the plurality of lamps 136, a lamp 136 and A reflection plate 114 disposed between the case 134 to prevent leakage of light generated from the lamp 136 and reflecting the light, and an optical member 510 to diffuse and collect light generated from the lamp 136. It is provided.

Each of the lamps 136 includes a glass tube, inert gases inside the glass tube, and a cathode and an anode installed at both ends of the glass tube. Inert gas is filled in the glass tube, and phosphor is coated on the inner wall of the glass tube. Each of the plurality of lamps 136, when the AC voltage from the inverter is applied to the high voltage electrode and the low pressure electrode, electrons are emitted from the low pressure electrode collides with the inert gas inside the glass tube to increase the amount of electrons exponentially. . Thereafter, electric current flows inside the glass tube by the increased electrons, and ultraviolet rays are emitted as the inert gas is excited by the electrons. Ultraviolet rays emitted in this manner collide with the luminescent phosphor applied to the inner wall of the glass tube to emit visible light.

The case 134 housing the plurality of lamps 136 is generated in the lamps 136 by reflecting visible light traveling toward the side and the back of the plurality of lamps 136 toward the front, that is, the optical member 510. The path of the light to be converted. In this case 134, a plurality of lamps 136 are arranged at regular intervals.

The reflective plate 114 is disposed between the upper surface of the case 134 and the plurality of lamps 136 to convert a path of light irradiated in the opposite direction of the liquid crystal display panel 102 among the light generated from the lamps 136. Irradiation toward the display panel 102 improves the efficiency of light.

The optical member 510 diffuses the light emitted from the lamps 136 and changes the path of the light so that the light incident on the liquid crystal display panel 102 can be directly directed to the liquid crystal display panel 102. The front luminance of the liquid crystal display panel 102 is improved. As the optical member 510, at least one of the optical members 110, 210, 310, and 410 suggested in the first to fourth embodiments of the present invention may be used.

As described above, the optical sheet and the backlight unit including the optical sheet according to the embodiment of the present invention can dramatically improve the light condensing efficiency of the light irradiated from the lamp to achieve high brightness of the liquid crystal display and improve the contrast. . In addition, the optical sheet and the backlight unit including the optical sheet according to the embodiment of the present invention can minimize the light loss caused by the conventional side lobe by providing the reflective region.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (9)

A support layer for transmitting light incident from the outside; And a reflective layer formed on the support layer and partially exposing the support layer and having an inclined surface. The method of claim 1, The reflective layer A first shape in which a triangular cross section is triangular and extends in a longitudinal direction and is arranged at regular intervals, A second shape in which the cross section is a triangular column extending in the longitudinal direction and arranged in a lattice form, A third shape in which pyramidal prisms extending in a triangular pyramid form are arranged in a predetermined direction and each array is spaced apart from each other, An optical sheet comprising at least one of a fourth form in which a pyramidal prism extending in a triangular pyramid form is arranged in a lattice form. The method of claim 1, The reflective layer Arranged at regular intervals, The triangular prism and the triangular pyramid-shaped edges are formed of at least one of a trapezoidal shape and a rounded round shape. The method of claim 1, The area where the reflective layer is in contact with the support layer is An optical sheet for transmitting light incident from the outside. The method of claim 1, The material of the reflective layer is Metallic materials such as nickel (Ni), chromium (Cr), aluminum (AL) and aluminum oxide (Al ₂ O ₃ ); Non-metallic materials such as reinforced plastic, glass, acrylic, And at least one of materials for forming the diffusion layer. The method of claim 1, The support layer An optical sheet comprising a diffusion layer for diffusing light incident from the outside. A support layer through which light is transmitted, Having a protrusion integrated with the support layer and protruding at an angle from the surface of the support layer and arranged such that the support layer is partially exposed, And the surface of the protrusion is reflective surface treated. In the backlight unit in which a plurality of light sources are installed in the liquid crystal display device, And a support layer formed on the support layer for transmitting light incident from the outside, and an optical sheet having a reflective layer having an inclined surface and partially exposing the support layer. The method of claim 8, The reflective layer A first shape in which a triangular cross section is triangular and extends in a longitudinal direction and is arranged at regular intervals, A second shape in which the cross section is a triangular column extending in the longitudinal direction and arranged in a lattice form, A third shape in which pyramidal prisms extending in a triangular pyramid form are arranged in a predetermined direction and each array is spaced apart from each other, An optical sheet comprising at least one of a fourth form in which a pyramidal prism extending in a triangular pyramid form is arranged in a lattice form.

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